This project is concerned with the evaluation of a variety of new and existing diagnostic techniques which have yet to be applied to biomedical diagnostic applications having particular relevance to dentistry. It is largely a continuation of work done in previous years which dealt with the development of quantitative methods for measuring factors believed to be associated with relatively long-term changes of diagnostic interest in dental tissues. Modalities studied include magnetic resonance imaging (MRI), nuclear medicine 99mTC-MDP), fiber-optic systems making use of visible light (hemoglobin-specific differential spectrum analysis and micro-fluorescent optical transducers). MRI was found to be particularly useful in imaging the capsular tissues of the temporomandibular joint including the meniscus. Also seen to advantage with this tool were periodic vascular changes in the nasal mucosae known as the nasal cycle and spontaneous salivary secretions. Preliminary data from two beagle dogs suggest that differential uptake of 99mTC-MDP predicted changes in the dynamics of wound healing in periodontal bone even before lesions were induced surgically in these animals. In vitro data obtained using a prototype filtered fiber-optical system designed to detect the presence of oxygenated blood in the pulp chamber of vital teeth confirm theoretical predictions that tiny amounts of fresh blood can be detected reliably irrespective of the angulation of the fiber-optic probe or the color of the light reaching the differential detector. Fiberoptics are also being investigated as means for measuring the oxygen tension of periodontal tissues in vivo. This technology makes use of chromic differences, induced in a dye sensitive to the presence of oxygen, to monitor the concentration of this gas in tissues of diagnostic interest. Such as plaque situated deep in a periodontal pocket.